The sensitivity of the human eye is dependent on the light intensity conditions. At low light intensities, <0.01 cd/m2, referred to as scotopic conditions, at which vision is mediated by rod cells, the eye is more sensitive to relatively short wavelengths, with a sensitivity peak at around 507 nm. In contrast, at high light intensity conditions, >3 cd/m2, referred to as photopic conditions and at which vision is mediated mainly by cone cells, the eye is more sensitive to longer wavelengths, with a sensitivity peak at 555 nm.
WO 2006/132533 aims to provide a lighting arrangement for public spaces which combines high efficiency with good visibility at night-time. To this end WO 2006/132533 proposes a lighting arrangement comprising a solid-state light source suitable for generating light of a first wavelength region and a second wavelength region. The first wavelength region comprises wavelengths of 500-550 nm, and the second wavelength region comprises wavelengths of 560-610 nm. The lighting arrangement is designed to generate light having a dominant wavelength from the first wavelength region in such a way that the eye sensitivity of the human eye is dominated by rods (i.e. scotopic vision).
However, a drawback of the solution proposed in WO 2006/132533 is that at positions directly below the lighting arrangement, color recognition is still unsatisfactory. Hence, there is a need in the art for improved lighting arrangements that are suitable for outdoor lighting.